1. Status report on MURAY telescope R&D
Pasquale Noli
on behalf of Mu-Ray collaboration

2. Outline Motivation Measurement principles The MURAY telescope
Fiber optical connector
SiPM hybrid connector
SiPM from IRST-FBK test
Front End electronic and DAQ
Conclusions
23/09/2010
SIF 2010 Bologna

3. Motivation 1631 eruption Pompei eruption
Muon radiography: few hundreds m
Seismic,
gravimetric,
electromag.
methods:
Several km
Volcano-eruption dynamics mostly depend on
the gas content
the chemical composition of the magma
the lava-conduit dimensions and shape.
Traditional measurement methods :
gravimetric
seismological
electromagnetic
Have spatial resolutions of the order of several hundredmeters.
Muonradiographycan improve resolutions
by one order of magnitude. 50
300
200
Conduit length = 8000m
Gas content = 5 wt% 20
1631 eruption
Pompei eruption
100,000 ton/s
100
Simulated Mass eruption rate vs. Conduit
23/09/2010
SIF 2010 Bologna

4. Muon Radiography
Muon radiography is based on the measurement of the absorption of cosmic muons inside matter.
“The first application was realized in 1971 by Alvarez and collaborators for the search of unknown burial cavities in the Chephren pyramid.”
In recent years Tanaka and collaborators, from University of Tokyo, have demonstrated the possibility to use this technique, to study the internal structure of volcanoes.
The spatial resolution that can be obtained with this method is of the order of 10 m.
23/09/2010
SIF 2010 Bologna

5. Measurement principles (I) (No background hypothesis)
The observed number of muons is a function of the muon flux crossing the volcano volume seen along the direction (,) the absorption factor A, and the detector efficiency  :
In the limit of neglecting the  dependence of cosmic ray flux, the product of the muonflux times detector efficiency can be measured using special runs pointing to “free” sky region
Then the absorption can be evaluated as:
23/09/2010
SIF 2010 Bologna

6. Measurement principles (II)
Starting from the theoretical muon flux distribution f (Thompson and Whalley expression) , we compute the expected muon transmission rate through water meter equivalent for each  direction.
For each (θ,) direction we can obtain the mean rock density from the ratio between:
the water meter equivalent length relative to A.
thickness of montain. .
23/09/2010
SIF 2010 Bologna

7. The MURAY telescope (I)
Two 2x2 m2 X-Y stations
Triangular shape scintillators (from Fermilab)
Scint. light collected by WLS one-side mirrored fiber
(BCF92 fast response fibers from Bicron)
Dedicated 32 fibers optical connector
Dedicated SiPM from FBK-IRST .
They have 1.4 mm diameter and 70x70 mm2
cell size, with 292 cells in total
Dedicated hybrid hosting 32 SiPMs
SiPM temperature control by Peltier Cells
SPIROC 0 ASIC FEE (from Orsay group)
Dedicated read-out and acquisition board
Expected performances:
≈3 mm space resolution (by measurement of
charge sharing between two adjacent strips)
≈ 1ns time resolution
O(10) W power consumption
23/09/2010
SIF 2010 Bologna

8. The MURAY telescope (II)
32 scintillator bars module (0.5 m large), with bars glued together and on a G11 fiberglass support plate
0.5 m
Fibers’ connector
2 m
SiPM hybrid connector
23/09/2010
SIF 2010 Bologna

9. The MURAY telescope prototype (I)
A prototype is under construction
3 X-Y stations 1x1 m2 area
SPIROC 1 ASIC FEE
A special tool designed and built for precision assembly of the 32 bars in a plane
23/09/2010
SIF 2010 Bologna

10. Fiber optical connector
A special connector (made of black Plexiglas) has been developed for high-precision positioning of the fibers in front of the SiPMs.
32 fibers are glued on the connector that will be fixed to the module chassis.
The fiber connector is mechanically coupled with a hybrid circuit hosting the SiPMs.
Al PROTOTIPE
SIPM SIDE
FIBER SIDE
Al prototype
O RING SEAT
MAGNIFICATION OF THE GLUE TANKS
Reference hole
23/09/2010
SIF 2010 Bologna

11. SiPM hybrid connector
In order to optimize the cooling by Peltier cells, we decided to group together
32 die SiPM in a single PCB.
One side of the Peltier cells is thermally in contact with the back side of the PCB.
A rubber O-ring ensures light and air tightness.
Two temperature sensors are located on the PCB for the Peltier cells control circuit.
The first 5 hybrid PCB have been produced in Florence.
23/09/2010
SIF 2010 Bologna

12. First test on SiPM
We studied the V break-down of the SiPM of first hybrid connector.
23/09/2010
SIF 2010 Bologna

13. Front End electronic and DAQ (I)
Spiroc 1: we have 18 chips, enough for the 1x1 m2 prototype
The FE board (Slave) and the trigger-DAQ board (Master) have been designed. The first prototypes have been realized and are under test.
SLAVE
MASTER
23/09/2010
SIF 2010 Bologna

14. Conclusions
We are presently assembling the first MU-RAY prototype module
The SiPMs produced at IRST-FBK are assembled on hybrid connector and are under test in Naples.
A special optical connector with SiPMs and Peltiercooling has been designed and built.
The readout electronics has been designed and is under test.
23/09/2010
SIF 2010 Bologna